Telescopic arm limiting method of crawler belt self-elevating type material distributing machine

Abstract

The invention provides a telescopic arm limiting method of a crawler belt self-elevating type material distributing machine, and is suitable for the technical field of concrete transportation. The method comprises the following steps: determining the maximum flow velocity of fresh concrete, calculating an inclination angle threshold value, arranging a telescopic arm dynamic limiting device and constructing a multi-parameter cooperative monitoring system, and determining the maximum flow velocity of the fresh concrete by establishing a relational expression between the inclination angle of the telescopic arm of the crawler self-elevating distributing machine and the flow velocity v of the fresh concrete. The maximum flow velocity of concrete is controlled by limiting the inclination angle of the telescopic arm; through a parameter optimization algorithm driven by historical data, the accuracy of theoretical calculation of the maximum flow velocity of concrete can be maintained when rheological property drifting is caused by equipment abrasion; the response time of angle overrun can be greatly shortened through PID algorithm adjustment in the dual-redundancy control module, the mechanical limiting provides limiting which is slow in response but more stable, and the risk that fresh concrete is separated and the impact load of a formwork exceeds the standard due to the fact that the flow speed is too high in the dynamic amplitude variation operation is effectively prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete transportation, and in particular to a telescopic arm limiting method of a crawler self-elevating concrete placing boom. Background Art

[0002] Traditional crawler-type self-elevating concrete placing booms fail to consider concrete flow velocity control during the pumping and pouring process. When the telescopic boom is tilted downward at an excessively large angle, the fresh concrete, driven by gravitational potential energy, forms an unsteady flow. The initial velocity at the outlet exceeds a critical value, triggering segregation phenomena such as aggregate separation and slurry splashing. This not only reduces the strength of the concrete structure but also causes quality defects such as excessive formwork impact loads and honeycombing of the poured surface. Current industry standards specify a maximum pouring height of less than 6 meters, but fail to account for the effects of excessive fresh concrete velocity caused by unsteady flow. Therefore, limit control of the telescopic boom's tilt position is required to prevent these adverse effects of excessive fresh concrete velocity. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems of aggregate separation, slurry splashing and quality defects caused by the excessively fast flow rate of fresh concrete in existing crawler self-elevating concrete placing booms. A telescopic arm limiting method for crawler self-elevating concrete placing booms is proposed, which can be widely used in the field of concrete transportation technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for limiting the telescopic arm of a crawler self-elevating concrete placing boom comprises the following steps:

[0006] S100, determine the maximum flow rate of fresh concrete, including the maximum pouring height h allowed during concrete pouring max Set the maximum flow rate v of fresh concrete flowing out of the telescopic arm outlet max During the concrete pouring process, the freshly mixed concrete flows out through the conveying channel in the telescopic arm;

[0007] S200, calculating the tilt angle threshold, including using the non-Newtonian fluid motion equation to establish a corresponding relationship between the tilt angle θ and the fresh concrete flow rate v, where the tilt angle is the tilt angle between the telescopic arm and the horizontal plane, and the fresh concrete flow rate v=v max Substitute into the relationship and solve the tilt angle threshold θ max ;

[0008] S300, deploying the dynamic limit device of the telescopic arm, including installing the dynamic limit device at the pitch rotation position of the telescopic arm of the placing machine, monitoring the inclination angle of the telescopic arm in real time through the angle sensor, comparing the inclination angle data obtained by monitoring with the inclination angle threshold, and when it exceeds θ maxAutomatically trigger the hydraulic system lock when

[0009] S400, build a multi-parameter collaborative monitoring system, including installing a non-contact flow meter at the outlet of the telescopic arm to measure the surface flow velocity v' of the fresh concrete at the outlet of the telescopic arm in real time, and calibrating the surface flow velocity and the inclination angle data. When the surface flow velocity is greater than v max The tilt angle does not reach θ max When the flow rate equation is reached, the current parameter values, concrete grade, concrete mix ratio and conveying channel size information in the flow rate equation are recorded in the database, the compensation algorithm is started to correct the flow rate equation, and the inclination angle threshold is updated.

[0010] As a preferred technical solution of the present invention, in step S100, the maximum flow velocity of concrete v max Specifically,

[0011]

[0012] Where, v max - Maximum flow rate of concrete, m / s, h max - Maximum pouring height, m, h- Actual pouring height, m, g- Gravitational acceleration, m / s 2 .

[0013] As a preferred technical solution of the present invention, in step S200, the non-Newtonian fluid motion equation adopts an improved Bingham fluid model.

[0014]

[0015] Where, τ is the shear stress of fresh concrete, Pa, τ0 is the initial shear yield stress of fresh concrete, Pa, μ is the plastic viscosity of fresh concrete, Pa·s, v is the flow velocity of fresh concrete, m / s, R h - hydraulic radius, m; Combined with the inclination angle θ of the telescopic arm and the extension length L, the flow velocity equation of fresh concrete during the pouring process is established.

[0016]

[0017] Where, ρ is the density of fresh concrete, kg / m 3 .

[0018] As a preferred technical solution of the present invention, in step S300, the dynamic limit device includes a dual redundant control module, the main control unit uses a PID algorithm to adjust the pitch rotation angle of the telescopic arm, that is, the tilt angle of the telescopic arm, and the backup unit is provided with a mechanical hard limit block; when the pitch rotation angle of the telescopic arm is raised or lowered by a sling, the tilt angle is positive when the outlet end of the telescopic arm is facing downward, and the conversion relationship between the tilt angle and the sling length is,

[0019]

[0020] Where, L a1 - The distance between the connection between the sling and the main support frame and the connection between the telescopic arm and the main support frame, m, L b1 - The distance between the connection between the sling and telescopic arm and the connection between the telescopic arm and the main support frame, m, L c1 - sling length, specifically the length from the sling to the main support frame to the sling to the telescopic arm connection, m; the telescopic arm pitch angle is when the hydraulic cylinder-type support arm lifts or lowers the telescopic arm, with the telescopic arm outlet facing downward, the tilt angle is positive, and the conversion relationship between the tilt angle and the hydraulic cylinder stroke is:

[0021]

[0022] Where, L a2 - The distance between the connection between the supporting arm and the supporting main frame and the connection between the telescopic arm and the supporting main frame, m, L b2 - The distance between the connection between the support arm and the telescopic arm and the connection between the telescopic arm and the main support frame, m, L c2 - Initial length of the support arm when the hydraulic cylinder stroke is 0, m, ΔL c2 -Hydraulic cylinder stroke, m.

[0023] As a preferred technical solution of the present invention, in step S400, the compensation algorithm includes:

[0024] S410, calculating a relative error, comparing the surface flow velocity measured in step S400 with the fresh concrete flow velocity calculated in step S200, and calculating a relative error Δv = |v′-v|;

[0025] S420, parameter optimization, if v′>v max And θ<θ max , triggering the compensation mechanism. According to the concrete grade, concrete mix ratio and conveying channel size information of the current project, the parameter values of historical projects with the same concrete grade, concrete mix ratio and conveying channel size are obtained from the database. Then, the parameter values of the current project and the parameter values of historical projects are combined to optimize the plastic viscosity and hydraulic radius of the fresh concrete using the gradient descent method.

[0026] S430: Threshold update: Substitute the optimized plastic viscosity and hydraulic radius into the velocity equation and recalculate the inclination angle threshold θ′ max , and updated to the dynamic limit device.

[0027] The beneficial effects of the present invention are: 1. By establishing a relationship between the inclination angle of the telescopic arm of a crawler self-elevating concrete placing boom and the flow rate v of fresh concrete, the maximum flow rate of concrete is proposed, and then the inclination angle of the telescopic arm is limited, thereby ensuring that there is no risk of segregation or excessive template impact load during the pouring of fresh concrete; 2. Through a parameter optimization algorithm driven by historical data, the accuracy of the theoretical calculation of the maximum flow rate of concrete can be maintained when the rheological characteristics drift due to equipment wear; 3. The PID algorithm adjustment in the dual redundant control module will greatly reduce the response time of the angle exceeding the limit, and the mechanical limit provides a slower but more stable limit, effectively preventing the risk of aggregate segregation caused by excessive flow rate of fresh concrete during dynamic amplitude variation operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of a telescopic arm limiting method of a crawler self-elevating concrete placing crane of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the support arm connected to the telescopic arm of the crawler self-elevating concrete placing machine of the present invention;

[0030] Reference numerals in the figure: 1-telescopic arm, 2-support main frame, 3-support arm. DETAILED DESCRIPTION

[0031] The following describes in detail specific embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments provided herein are intended only to illustrate and explain the present invention and are not intended to limit the present invention. It should be noted that many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention may also have other embodiments and variations thereof. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0032] In the first embodiment, a method for limiting the telescopic arm of a crawler self-elevating concrete placing boom is as follows:

[0033] S100, determine the maximum flow rate of fresh concrete, including the maximum pouring height h allowed during concrete pouring max Set the maximum flow rate v of fresh concrete flowing out of the outlet of telescopic arm 1 max During the concrete pouring process, the freshly mixed concrete flows out through the conveying channel in the telescopic arm 1; according to the "General Code for Concrete Structures" GB 55008-2021, segregation shall not occur when pouring concrete in column and wall formwork, and the pouring height shall have different limits depending on the size of the coarse aggregate. When the coarse aggregate size is greater than 25mm, the pouring pouring height shall not exceed 3m; when the coarse aggregate size is less than or equal to 25mm, the pouring pouring height shall not exceed 6m; the concrete flow rate in the traditional pouring method is very low, that is, the initial velocity is almost 0, and the gravitational potential energy of the pouring height is converted into kinetic energy. When the concrete is poured, the maximum velocity of the collision with the formwork is When using a crawler self-elevating concrete placing boom, its telescopic arm 1 causes the flow path of fresh concrete to be longer than that of an ordinary concrete placing boom, and the inclination angle is relatively large. The influence of the concrete flow rate cannot be ignored. Therefore, the maximum flow rate of concrete when flowing out of the conveying channel is v max Specifically,

[0034]

[0035] Where, v max - Maximum flow rate of concrete, m / s, h max - Maximum pouring height, m, h- Actual pouring height, m, g- Gravitational acceleration, m / s 2 ;

[0036] S200, calculating the tilt angle threshold, including using the non-Newtonian fluid motion equation to establish a corresponding relationship between the tilt angle θ and the fresh concrete flow rate v, where the tilt angle is the tilt angle of the telescopic arm 1 to the horizontal plane, and the fresh concrete flow rate v=v max Substitute into the relationship and solve the tilt angle threshold θ max ; The non-Newtonian fluid motion equation adopts an improved Bingham fluid model,

[0037]

[0038] Where, τ is the shear stress of fresh concrete, Pa, τ0 is the initial shear yield stress of fresh concrete, Pa, μ is the plastic viscosity of fresh concrete, Pa·s, v is the flow velocity of fresh concrete, m / s, R h - hydraulic radius, m; considering the force balance of the concrete element along the flow direction (x-axis), the acceleration term is introduced:

[0039]

[0040] Where, ρ is the density of fresh concrete, kg / m 3 , A- fresh concrete flow cross-sectional area, calculated according to the cross-sectional area of the conveying channel, m 2 , P-wetted perimeter, calculated according to the perimeter of the conveying channel, m; use the chain rule to convert the time variable into a space variable,

[0041]

[0042] And R h =A / P; Solving differential equation (4) yields the implicit function of the flow rate of fresh concrete during the pouring process with respect to the inclination angle θ of the telescopic arm 1 and the extension length L,

[0043]

[0044] Where, ρ is the density of fresh concrete, kg / m 3 ;

[0045] S300, deploying the dynamic limit device of the telescopic arm, including installing the dynamic limit device at the pitch rotation position of the telescopic arm 1 of the material placing machine, monitoring the inclination angle of the telescopic arm 1 in real time through the angle sensor, comparing the inclination angle data obtained by monitoring with the inclination angle threshold, and when it exceeds θ max The hydraulic system is automatically locked when the hydraulic system is locked; the dynamic limit device includes a dual redundant control module, the main control unit uses a PID algorithm to adjust the pitch rotation angle of the telescopic arm 1, that is, the tilt angle of the telescopic arm 1, and the backup unit is provided with a mechanical hard limit block; the pitch rotation angle of the telescopic arm 1 adopts a hydraulic cylinder-shaped support arm 3. When the telescopic arm is lifted or lowered, the tilt angle is positive when the outlet end of the telescopic arm 1 faces downward. The conversion relationship between the tilt angle and the hydraulic cylinder stroke is:

[0046]

[0047] Where, L a2 - Distance between the connection between the support arm 3 and the support main frame 2 and the connection between the telescopic arm 1 and the support main frame 2, m, L b2 - Distance between the connection between support arm 3 and telescopic arm 1 and the connection between telescopic arm 1 and support main frame 2, m, L c2 - Initial length of support arm 3 when hydraulic cylinder stroke is 0, m, ΔL c2 - hydraulic cylinder stroke, m;

[0048] S400, build a multi-parameter collaborative monitoring system, including installing a non-contact flow meter at the outlet of telescopic arm 1 to measure the surface flow velocity v' of fresh concrete at the outlet of telescopic arm 1 in real time, and calibrating the surface flow velocity and inclination angle data. When the surface flow velocity is greater than v max The tilt angle does not reach θ max When the flow rate equation is set, the current parameter values, concrete grade, concrete mix ratio and conveying channel size information in the flow rate equation are recorded in the database, and the compensation algorithm is started to correct the flow rate equation and update the inclination angle threshold; the compensation algorithm includes:

[0049] S410, calculating a relative error, comparing the surface flow velocity measured in step S400 with the fresh concrete flow velocity calculated in step S200, and calculating a relative error Δv = |v′-v|;

[0050] S420, parameter optimization, if v′>v max And θ<θ max, triggering the compensation mechanism. According to the concrete grade, concrete mix ratio and conveying channel size information of the current project, the parameter values of historical projects with the same concrete grade, concrete mix ratio and conveying channel size are obtained from the database. Then, the parameter values of the current project and the parameter values of historical projects are combined to optimize the plastic viscosity and hydraulic radius of the fresh concrete using the gradient descent method.

[0051] S430: Threshold update: Substitute the optimized plastic viscosity and hydraulic radius into the velocity equation and recalculate the inclination angle threshold θ′ max , and updated to the dynamic limit device.

[0052] The second embodiment is different from the first embodiment in that the pitching angle of the telescopic arm is to lift or lower the telescopic arm by a sling. When the outlet end of the telescopic arm faces downward, the tilt angle is positive. The conversion relationship between the tilt angle and the sling length is:

[0053]

[0054] Where, L a1 - The distance between the connection between the sling and the main support frame and the connection between the telescopic arm and the main support frame, m, L b1 - The distance between the connection between the sling and telescopic arm and the connection between the telescopic arm and the main support frame, m, L c1 - Sling length, specifically refers to the length of the sling from the connection between the sling and the supporting main frame to the connection between the sling and the telescopic arm, in meters.

[0055] In summary, the telescopic arm limiting method of a crawler self-elevating concrete placing boom of the present invention has the characteristics of ensuring the quality of concrete pouring and reducing the risk of excessive impact load on the formwork in the field of concrete transportation technology.

[0056] It should be understood that the above embodiments are one or more embodiments of the present invention, and there are many other embodiments and variations thereof based on the present invention; the variations and modifications made by ordinary technicians in this industry through the present invention without making groundbreaking innovations all fall within the scope of protection of the present invention.

Claims

1. A method for limiting the telescopic arm of a crawler self-elevating concrete placing boom, characterized in that: The following steps are involved: S100, determine the maximum flow rate of fresh concrete, including the maximum pouring height h allowed during concrete pouring max Set the maximum flow rate v of fresh concrete flowing out of the telescopic arm outlet max During the concrete pouring process, the freshly mixed concrete flows out through the conveying channel in the telescopic arm; S200, calculating the tilt angle threshold, including using the non-Newtonian fluid motion equation to establish a corresponding relationship between the tilt angle θ and the fresh concrete flow rate v, where the tilt angle is the tilt angle between the telescopic arm and the horizontal plane, and the fresh concrete flow rate v=v max Substitute into the relationship and solve the tilt angle threshold θ max ; S300, deploying a dynamic limiter for the telescopic arm, including installing a dynamic limiter at the pitching position of the telescopic arm of the placing machine, monitoring the inclination angle of the telescopic arm in real time through an angle sensor, comparing the inclination angle data obtained by monitoring with the inclination angle threshold, and when it exceeds θ max Automatically trigger the hydraulic system lock when S400, build a multi-parameter collaborative monitoring system, including installing a non-contact flow meter at the outlet of the telescopic arm to measure the surface flow velocity v' of the fresh concrete at the outlet of the telescopic arm in real time, and calibrating the surface flow velocity and the inclination angle data. When the surface flow velocity is greater than v max The tilt angle does not reach θ max When the flow rate equation is reached, the current parameter values, concrete grade, concrete mix ratio and conveying channel size information in the flow rate equation are recorded in the database, the compensation algorithm is started to correct the flow rate equation, and the inclination angle threshold is updated.

2. The telescopic arm limiting method of a crawler self-elevating concrete placing crane according to claim 1, characterized in that: In step S100, the maximum concrete flow rate v max Specifically, Where, v max - Maximum flow rate of concrete, m / s, h max - Maximum pouring height, m, h- Actual pouring height, m, g- Gravitational acceleration, m / s 2 .

3. The telescopic arm limiting method of a crawler self-elevating concrete placing crane according to claim 1, characterized in that: In step S200, the non-Newtonian fluid motion equation adopts an improved Bingham fluid model. Where, τ is the shear stress of fresh concrete, Pa, τ0 is the initial shear yield stress of fresh concrete, Pa, μ is the plastic viscosity of fresh concrete, Pa·s, v is the flow velocity of fresh concrete, m / s, R h - hydraulic radius, m; Combined with the inclination angle θ of the telescopic arm and the extension length L, the flow velocity equation of fresh concrete during the pouring process is established. Where, ρ is the density of fresh concrete, kg / m 3 .

4. The telescopic arm limiting method of a crawler self-elevating concrete placing crane according to claim 1, characterized in that: In step S300, the dynamic limit device includes a dual redundant control module. The main control unit uses a PID algorithm to adjust the pitch rotation angle of the telescopic arm, that is, the tilt angle of the telescopic arm. The backup unit sets a mechanical hard limit block. When the telescopic arm pitch rotation angle is raised or lowered by a sling, the tilt angle is positive when the outlet end of the telescopic arm is facing downward. The conversion relationship between the tilt angle and the sling length is: Where, L a1 - The distance between the connection between the sling and the main support frame and the connection between the telescopic arm and the main support frame, m, L b1 - The distance between the connection between the sling and telescopic arm and the connection between the telescopic arm and the main support frame, m, L c1 - sling length, specifically the length from the sling to the main support frame to the sling to the telescopic arm connection, m; the telescopic arm pitch angle is when the hydraulic cylinder-type support arm lifts or lowers the telescopic arm, with the telescopic arm outlet facing downward, the tilt angle is positive, and the conversion relationship between the tilt angle and the hydraulic cylinder stroke is: Where, L a2 - The distance between the connection between the supporting arm and the supporting main frame and the connection between the telescopic arm and the supporting main frame, m, L b2 - The distance between the connection between the support arm and the telescopic arm and the connection between the telescopic arm and the main support frame, m, L c2 - Initial length of the support arm when the hydraulic cylinder stroke is 0, m, ΔL c2 -Hydraulic cylinder stroke, m.

5. The telescopic arm limiting method of a crawler self-elevating concrete placing crane according to claim 1, characterized in that: In step S400, the compensation algorithm includes: S410, calculating a relative error, comparing the surface flow velocity measured in step S400 with the fresh concrete flow velocity calculated in step S200, and calculating a relative error Δv = |v′-v|; S420, parameter optimization, if v′>v max And θ<θ max , triggering the compensation mechanism. According to the concrete grade, concrete mix ratio and conveying channel size information of the current project, the parameter values of historical projects with the same concrete grade, concrete mix ratio and conveying channel size are obtained from the database. Then, the parameter values of the current project and the parameter values of historical projects are combined to optimize the plastic viscosity and hydraulic radius of the fresh concrete using the gradient descent method. S430: Threshold update: Substitute the optimized plastic viscosity and hydraulic radius into the velocity equation and recalculate the inclination angle threshold θ′ max , and updated to the dynamic limit device.

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